JavaScript: UndoManager

UndoManager.js

this.sample = this.sample || {};

(function () {

    /**
     *
     * @constructor
     */
    var UndoManager = function () {
        this.initialize();
    }, p = UndoManager.prototype;

    /**
     *
     */
    p.initialize = function () {
        this.didCommands = [];
        this.undidCommands = [];
    };

    /**
     *
     * @return {Boolean}
     */
    p.canUndo = function () {
        return Boolean(this.didCommands.length > 0);
    };

    /**
     *
     * @return {Boolean}
     */
    p.canRedo = function () {
        return Boolean(this.undidCommands.length > 0);
    };

    /**
     *
     * @param command
     */
    p.push = function (command) {
        this.didCommands.push(command);
        // @TODO
        this.undidCommands = [];
    };

    /**
     *
     */
    p.undo = function () {
        if (this.canUndo()) {
            var command = this.didCommands.pop();
            this.undidCommands.push(command);
            if (typeof command.unexecute === 'function') {
                command.unexecute();
            }
        }
    };

    /**
     *
     */
    p.redo = function () {
        if (this.canUndo()) {
            var command = this.undidCommands.pop();
            this.didCommands.push(command);
            if (typeof command.execute === 'function') {
                command.execute();
            }
        }
    };

    sample.UndoManager = UndoManager;

})();